As known in the prior art, in connection with the reeling of a paper web, a reeling drum is used which is provided with suction zones of the sector type, i.e. suction takes place through holes situated in a suction drum shell only in part of the circumference of the drum in the area of a certain sector. One prior-art arrangement in the reeling of a paper web, using a reeling drum provided with a suction zone sector, is disclosed in FI patent 74446. In known arrangements in which the suction zone is formed into a sector, it is hardly at all possible to remove the boundary layer air flow produced by the rotating drum. In addition, the suction zone sector in known applications is situated outside the web in the length direction of the drum, i.e. in the width direction of the web, and for this reason during threading it has been necessary to guide the tail strip to the side, i.e. to the zone area, by means of blowing. In many cases, the location of the suction zone sector is also not optimal on the circumference of the drum because the tail strip typically misses the area of the suction sector in the threading operation. If the tail strip misses the suction zone, the tail strip slips out of the machine to the tending side, thus not entering the nip between the reeling drum and the reel spool, i.e. a holding/pulling point. The strip may also be directed towards the middle of the machine and it may slip into the nip from some unpredictable point. This leads to a random amount of loose strip. The tightening of the loose strip lengthens the time taken by threading unnecessarily. In many cases it does not even succeed, but breaks when it flaps and flutters into other structures of the machine. After unsuccessful threading attempts, the threading path must be cleared to remove broken tail strips in order that new attempts may be made, which in turn further increases the threading time unnecessarily. The arrangement known from FI patent 74446 is primarily intended to aid reeling in order that the reeling speed might be increased, when needed. This known arrangement does not teach threading of a web.
In the arrangements known from the prior art, the holes through which a suction effect is arranged to be produced, are generally placed in the ridges between the grooves of grooved drums.
With respect to the state of the art relating to the threading of a paper web in connection with finishing devices, reference may be made, for example, to FI patent 98742, which discloses a method and an apparatus for threading a paper web on a surface treatment line for paper. In this known arrangement, the paper guide rolls and the surface treatment roll of the surface treatment line are provided with a suction sector and a blow sector, and by using them it is possible to cause the tail strip to adhere reliably to the perforated surface of the roll by means of the suction sector, and by means of suction it is possible to assure the right direction of the draw of the tail strip as well as the guidability of the draw, and formation of an air film between the paper web and the roll is avoided by means of the blow sector, and the tail strip is separated from the roll surface by means of blowing.
With respect to the prior art, reference can also be made to U.S. Pat. No. 5,915,648 disclosing a perforated roll for guiding a flexible material web, in particular a paper web, which has a jacket and a hollow interior and a respective cover at each end of the jacket. The jacket has a plurality of passage openings for passage of air therethrough, and at least one impeller inside the interior of the roll having a suction side for drawing air into the roll through the passage openings.